The tire vulcanization process is performed by placing a green tire in a mold and pressurizing and heating the green tire in a cavity formed by the mold and a bladder.
In this tire vulcanization process, gas is generated by cross-linking reaction. When the generated gas remains between the tire and the mold, a bare (flaw on the tire surface) is formed that causes deterioration of tire quality.
In order to discharge the gas into the outside air, a tire mold has been proposed in which a vent groove is provided on a bead ring to form a gas venting passage (saw-cut) (for example, Patent Document 1).